In the past, I 've had a problem with the small gray slugs getting on my lettuce, cole crops, etc. and tried the usual beer traps and the like. The trap caught lots of slugs, but didn't make a dent in their population. This summer I let my 8 ducks have full access to the garden and they spent a lot of time in there, especially in the early morning and evening. So with all of this wet weather we have been having lately in the Southeast, I went out to check my broccoli and cabbages for slugs and couldn't find a single one on any of them. I haven't had any noticeable problems with them trampling or eating any of the veggies growing in the garden.
My friend from Thailand used to have a job taking thousands of ducks to various rice paddies. If moved through an area quickly, they will eat all of the slugs but not bother the rice, since they prefer the high-protein, juicy morsel that a slug is.
Yep, I've had to do the same thing. If I leave my ducks out all day, they'll eat my pea plants, strawberries and young vegetables. So, now I just let them out for an hour or two while I garden and then put them back in their large fenced yard. It reduces the pests (especially slugs!), without reducing my plants .
My ducks have free access to many other parts of my property including pastures, bamboo groves, an aquaculture pond, and a lake, so they only go in the garden when the slugs and other goodies are out (early morning, evening, rains). The mallard type ducks I have now are much more terrestrial than the muscovy ducks I had previously who spent most of their time in and around the lake.
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